Novel photographic products and processes

ABSTRACT

LAYER HAVING ASSOCIATED THEREWITH DIFFUSION TRANSFER PROCESS DYE IMAGE-FORMING MATERIAL DISPOSED OM THE UNIT AS A SOLID DISPERSION FORMULATED IN ACCORDANCE WITH THE PRESENT INVENTION, A LAYER ADAPTED TO ECEIVE DYE IMAGE-FORMING MATERIAL DUFFUSING THERETO; AND TO SPECIFIED PROCESSES FOR THE PRODUCTION OF AND THE EMPLOYMENT OF THE DISPERSION INCLUDING PHOTOGRAPHIC PROCESSES SUCH AS DIFFUSION TRANSFER PHOTOGRAPHIC PROCESS EMPLOYING FILM UNITS CONTAINING SUCH DISPERSIONS.   THE PRESENT INVENTION RELATED TO SPECIFIED SOLID MATERIAL DISPERESIONS, PARTICULARLY TO PHOTOGRAPHIC FILM UNITS EMPLOYING SUCH DISPERSIONS AND, MORE PARTICULARLY, TO DIFFUSION TRANSFER PROCESS PHOTOGRAPHIC FILM UNITS WHICH COMPRISE A PHOTOSENSITIVE ELEMENT ADAPTED TO PROVIDE, BY DIFFUSION TRANSFER PHOTOGRAPHIC PROCESSING, SELECTIVE DYE IMAGE RECORDATION OF INCIDENT ACTINIC RADIATION AS A FUNCTION OF THE POINT-TO-POINT DEGREE OF PHOTOSENSITIVE ELEMENT EXPOSURE, WHICH FILM UNIT INCLUDES A PLURALITY OF ESSENTIAL LAYERS INCLUDING A PHOTOSENSITIVE SILVER HALIDE

1974 L. D.-CERANKOWSKI ErAL 3,882,

NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed'Dec. 12, 1972 4 Sheets-Sheet 1 Aug. 27, 1974 o. CERANKOWSKI T NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES 4 Sheets-Sheet 2 Filed Dec. 12, 1972 N 67 in Aug. 27, 1974 L. D. cERANKowsm 3,832,173

NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES 4 Sheets-Sheet 5 Filed Dec. 12, 1972 mm/P Aug. 27, 1974 L. D. CERANKO WSKI ETA!- 3,332,173

NOVEL PHOTO GRAPHIC PRODUCTS AND PROCESSES 4 Sheets-Sheet A v Filed Dec. 12, 1972 Patented Aug. 27, 1974 United States Patent Oflice ABSTRACT OF THE DISCLOSURE The present invention relates to specified solid mate-- rial dispersions, particularly to photographic film units employing such dispersions and, more particularly, to diffusion transfer process photographic film units which comprise a photosensitive element adapted to provide, by diffusion transfer photographic processing, selective dye image recordation of incident actinic radiation as a function of the point-to-point degree of photosensitive element exposure, which film unit includes a plurality of essential layers including a photosensitive silver halide layer having associated therewith diffusion transfer process dye image-forming material disposed in the unit as a solid dispersion formulated in accordance with the present invention, a layer adapted to receive dye image-forming material diffusing thereto; and to specified processes for the production of and the employment of the dispersions including photographic processes such as diffusion transfer photographic processes employing film units containing such dispersions.

, BACKGROUND OF THE INVENTION 1. Field of the Invention j The present invention is directed to providing new and improved solid material dispersions, particularly to photographic film units employing such dispersions and, more particularly, to diffusion transfer process photographic film units adapted to provide, as a function of the point-to-point degree of photoexposure, by diffusion transfer processing a dye transfer image.

2. Description of Prior Art As disclosed in U.S. Pat. No. 3,672,890 a composite photosensitive structure, particularly adapted for reflection type photographic diffusion transfer color process employment, which comprises a plurality of essential layers including, in sequence, a dimensionally stable layer preferably opaque to incident radiation; one or more silver halide emulsion layers having associated therewith In a preferred embodiment, the composite photosensitive structure includes a rupturable container, retaining an alkaline'processing composition and the opacifying agent, fixedly'positioned extending transverse' a leading edge of the'composite structure inorder to eflect, uponqi application of compressive pressure to the container; discharge of the processing composition intermediate. the opposed surfaces of the reception layer and the next-adjacent silver halide emulsion. i 1.

The liquid processing composition,"- distributed intermediate the; reception layefan'dtli'e silver halide emulsion permeatesthe silver halide emulsion layers of the composite photosensitive structure to initiate development of "the latentimages' contained: therein resultant ment off'the latent images, dye:image-providingmaterial associated with each-of the respective: silver halide emulsion layers 'is individually mobilized as a function of the point-to-point degree of the respective silver halide emulsion layers photoexposure, resulting in imagewise distributions of mobile dye image-providing materials adapted to transfer, by diffusion, to the reception layer to provide the desired transfer dye image. Subsequent to substantial dye image formation in the reception layer, means associated with composite structure are adapted to convert the pH of the film unit from a first processing pH at which dye image-providing material is diffusible as a function of the film units photoexposure to a second pH at which the transfer dye image exhibits increased stability, preferably a sufficient portion of the ions of an alkaline processing composition transfers, by diffusion, to a polymeric neutralizing layer to effect reduction in the alkalinity of the composite film unit from a first alkaline processing pH 'to the second pH at which dye imageproviding material is substantially nondilfusible, and further dye image-providing material transfer is thereby substantially obviated.

The transfer dye image is viewed, as a reflection image, through the dimensionally stable transparent layer against the background provided by the opacifying agent, distributed as a component of the processing composition, intermediate the reception layer and next adjacent silver halide emulsion layer. The thus-formed opacifying stratum effectively masks residual dye image-providing material retained in associated with the silver halide emulsion layer subsequent to processing.

In U.S. Pat. No. 3,415,644, the dimensionally stable layer of the film unit next adjacent the photosensitive layer or layers is disclosed to be opaque, the opacifying agent is initially disposed in an aqueous alkaline processing composition and the film units pH modulating means are disclosed to comprise a polymeric layer disposed intermediate the dimensionally stable transparent layer and the reception layer and adapted to reduce, subsequent 'to substantial dye transfer image formation, the pH of an aqueous alkaline processing composition from a first processing pH at which the dye image-forming material or materials are soluble and diffusible in the composition as a function of the photoexposure of the photosensitive 'silver halide layer associated therewith to a second pH 3,415,645, in such instance the opacifying agent may be 6 "initially disposed in the filin' unit'intermediate the recep- 0" tion layer and'next adjacent silver halide layer.

As disclosedin US. Pats. Nos 3,615,421 and 3,661,585, the opacifying componentof'the film unit may optionally be initially disposedjas a preformed processing composi- Qt'ion' permeable layefiiinter'mediate the reception layer and .nextadjacerit'silverhalide layer, in a concentration which prionto'photoexposure is insufficient to prevent transmisg sion'there'through of exposing actinic radiation and which,

subsequent tdprocjssing, possesses an opacifying capac- "ity effective to mask residual dye image-providing material. retained associated with the film.units silver halide .emulsion layers, and in U.S. Pat. NQ.'.3,647,435, the opaci- ,forming materials aredisclosed tocor npr ise adyefdevel- .velopingagent and which is jqrtefera Iy' vidually interposed intermediate ltli'e" silven halide layer and reception layer by selective distribution from a composite or a plurality of rupturable containers.

In U.S. Pat. No. 3,573,043, the polymeric neutralizing layer is disclosed to be optionally disposed intermediate the dimensionally stable opaque layer and next adjacent essential layer, i.e., next adjacent silver halide/dye imageproviding material component, to effect the designated modulation of film unit's environmental pH; Pat. No. 3,576,625 discloses the employment of particulate acid distributed within the film unit to effect the modulation of the environmental pH, and U.S. Pat. No. 3,573,- 044 discloses the employment of processing composition solvent vapor transmissive dimensionally stable layers to effect process modulation of dye transfer as a function of solvent concentration.

Where desired, the film unit may also be constructed in accordance with the disclosure of U.S. Pat. Nos. 3,594,- 164; 3,594,165; 3,689,262, and the copending U.S. patent application of Howard G. Rogers Ser. No. 159,254, filed July 2, 1971, now U.S. Pat. No. 3,778,265, to comprise a composite photosensitive structure including a transparent dimensionally stable layer carrying a reception layer, a processing composition permeable opaque layer and a photosensitive silver halide layer and the film unit may include a separate dimensionally stable sheet element adapted to be superposed on the surface of the photosensitive structure opposite the dimensionally stable layer and may further include means such as a rupturable container retaining processing composition for distribution of a processing composition intermediate the sheet and photosensitive structure to effect processing. As further disclosed in certain of the last-cited patients and applications, in structures wherein the receptor is positioned next adjacent the transparent layer orthe processing composition and/or the sheet is to be separated from the remainder of the film unit subsequent to processing, the latter elements may optionally include opacifying component.

As disclosed in U.S. Pat. No. 3,620,724, the dimensionally stable layer referred to may be opaque and in which instance the photosensitive silver halide layer is positioned; next adjacent the opaque support layer and the opacitying component of the film units processing composition permeable opaque layer will be disposed in the unit in a concentration insufficient to prevent transmission therethrough of exposing actinic radition and which, subsequent to processing, possesses an opacifying capacity effective to mask residual dye image-providing material retained associated with the silver halide layer, and as disclosed in U.S. Pat. No. .3,647,434,,theopacifying,agent maybe optionally formedin such film.,uni t, .infsit ifduring proc;;,-, ,essing of the unit. 1 I V .In the aforementioned U.S. patents, preferredrdye imageoper, that is, a dye,wh ich constitutespsilverihalide de- I P y z solid dispersion possessing 'Ia 'partic i'stribution wherein at least SO percent andprejfe'r a least 7 5 ;p'ercent of the dyeparticlesposses's a' di about one'micron and, most preferably, ters Erbbiit 0 micron, disposed in thefil'm unit atac'on'c'e'ntrat'ion within them,

halide associated with the dye" me'asured as' -'silver,-'by

weight, dispersed in an alkaline solution permeable polyessays meric matrix at a concentration within the range of about 0.1 to 25 mgs. of dye per mg. of polymer, by weight.

Summary of the Invention tive/positive, diffusion transfer process photographic film unit adapted to provide, by diffusion transfer processing, photographic color image reproduction as a function of exposure of such film unit to incident actinic radiation,

In accordance with the present invention, solid dispersions may be provided which possess a particle size distribution below that at which a dispersion exhibits the tyndall effect, that is, scattering of light by the small particles of the dispersion, e.g., solid dispersions comprising a sufficient proportion of its constituent particles below about 0.01 micron, and, accordingly, microdispersions which do not refract visible electromagnetic radiation incident on such dispersions.

Specifically, the solid dispersions of the present invention may be formulated by 'disposing a polymer and a selected solid material, to be constituted in the form of a microdispersion, in a first solvent in which the polymer and the solid material is soluble and disposing the resultant polymer/solid material first solvent solution in a second solvent in which the first solvent is miscible, the polymer is soluble and the solid material is insoluble, and when desired dissociating the first solvent polymer solution from the remainder of the mixture.

The preferred film unit assemblage construction to be employed in the practice of the present invention comprises a film unit of the general type set forth in aforementioned U.S. Pats. Nos. 3,415,644; 3,415,645; 3,414,- 646; 3,473,925; 3,573,042; 3,573,043; 3,573,044; 3,576,- 625; 3,576,626; 3,594,164; 3,594,165; 3,615,421; 3,620,- 724; 3,647,434; 3,647,435; 3,647,437; 3,661,585; 3,672; 890; and 3,689,262; and copending U.S. patent application Ser. No. 159,254, now U.S. Pat. No. 3,689,262; and in U.S. Pats. Nos. 2,983,606 and 3,345,163; and copending U.S. patent application Ser. No. 262,332, filed June 13, 1972. Specifically, such film unit construction will'comprise a plurality of layers including, in relative order, a dimensionally stable layer preferably opaque to incident actinic radiation; one or more photosensitive silver halide layers having associated therewith one or more diffusion transfer process dye image-forming materials present in the form of a solid dispersion possessing the parameters set forth herein; a substantially transparent layer adapted to receive dye image-forming material diffusing thereto and, optionally, a dimensionally stable layer transparent to incident actinic radiation; means for providing, intermediate the silver halide layers and the reception layer, opacifying agent; and means for providing a processing composition in contact with the photosensitive layers, and, in a particularly preferred embodiment, a processing composition possessing a first pH at which the diffusion transfer process dye image-forming material is diffusible .dur-

ing-processing and means for modulating the pH of the film 'unit from the first pHto a second pH at which the dye image-forming material is substantially nondiffusible subsequent to substantial dye transfer image formation.

In accordance with a specifically preferred embodiment :of the present invention, a film unit assemblage of the I aforementioned general structural parameters will be adapted to be processed, subsequent to photoexposure, in

the presence of actinic radiation and maybe fabricated to employ, as -means interposed intermediate the reception layer and next adjjacent silver halide layer subsequent. to photoexposure, an inorganic light-reflecting pigment dispersion containing. reflecting pigment and at least-.one optical filter agent,;at a pH above thepKa of the .optical filter-agent and.at which pH the dye image-forming material'is diffusible during processing as a, function of-silver halide layer photoexposure-in .a concentration in admixture effective to provide a barrier to transmission of actinic radiation therethrough, and the means-for interposing the opacifying agent and the processing composition may comprise a rupturable container, retaining the opacifying agent disposed in the processing composition selected, fixedly positioned extending transverse a leading edge of the film unit and adapted, upon application of compressive pressure, to distribute its contents intermediate the reception layer and next adjacent silver halide layer.

' ICBRIEF DESCRIPTION OF THE DRAWINGS .of the various materials being exaggerated, and wherein FIG. 2 represents an exposure stage, FIG. 4 represents a processing stage and FIG. 6 represents a product of the process; and I FIGS. 3, 5 and 7 are diagrammatic, further enlarged cross-sectional views of the film unit of FIGS. 2, 4 and 6,

along section lines 33, 5--5 and 77, respectively, further illustrating, in detail, the arrangement of layers comprising the photosensitive laminate during the three illustrated stages of the transfer process.

. DETVAILEDIDESCRIPTION OF THE INVENTION .As previously characterized, diffusion transfer photographic processing may be employed to provide a positive reflection dye image, as a direct function of actim'c radiation incident on a film unit assemblage which unit is preferably constructed to comprise a plurality of sequential layers including a dimensionally stable layer most preferably opaque to incident radiation; a photosensitive silver halide layer having associated therewith dye image- :forming material which is processing composition diffusible at a selected first pH as a function of the pointto-point degree of silver halide layer photoexposure; a layer adapted to receive dye image-forming material diffusing thereto; a dimensionally stable layer transparent to incident radiation; means for. interposing intermediate the silver halide layer and the reception layer, opacifying agent, preferable an inorganic reflecting pigment dispersion containing at least one optical filter agent or dye, in a concentration effective to provide, subsequent to selective photoexposure of the silver halide layer, protection of the silver halide layer from further exposure to actinic radiation incident on the dimensionally stable layer; and means for converting the pH of the film unit from the first processing pH to a second pH at which the dye image-forming material is substantially nondiffusible subsequent to substantial dye image-forming material diffusion to the reception layer.

Itnow has been discovered, however, that improved photographic reproduction in color by diffusion transfer processing may be accomplished by employment of a diffusion transfer process film unit in which a dye imageforming material associated with photosensitive silver halide is disposed in the film unit as solid dispersionof particulate material possessing a particle size distribution below that at which a dispersion of the material exhibits the tyndal effect, e.g., a solid dispersion possessing a sufficient proportion of its constituent particles below about 0.01 micron.

Specifically, the stated solid, dyefimage-forming material dispersions have been ascertained to not only dissolve more rapidly and efficiently in phbtographic processing composition solvent by reason ofithe increased surface area available off-inferactionwith the siilventfper unit Weight of material, but, with respect toconventional dye image-forming materials employed in combination with the universally preferred alkaline photographic processing compositions and, in particular, alkaline processing composition soluble dye image-providing materials, it has been found that the pH required for optimum employment of the materials, in accordance with the present invention, is lower than that heretofore required for the employment of identical materials. The resultant decrease in required alkali concentration specifically facilitates the production of stable dye transfer images, in accordance with the present invention, by reduction in the quantum of pH reduction required to approximate the same degree of dye transfer image environment neutralization desired for image stability purposes. The advantages specified are in addition to certain film unit optical advantages achieved by reasons of the employment of the dispersions. Specifically, employment of the specified dispersions, by reason of their property of not scattering incident light employedfor selective exposure of the photosensitive element, allows for photographic image reproduction exhibiting acuity and resolution in excess of that presently afforded by the existing state of the relevant art.

In accordance with the present invention, the solid dispersions, comprising microdispersions which do not substantially refract or refiect visible light incident of the dispersion, are formulated by disposing the selected solid material to be dispersed in a first solvent in which the material is soluble and a polymer, soluble in the first solvent, in a concentration effective to prevent secondary solid dispersion grain or particle growth either by Ostwald ripening or by coagulation combined with recrystallization upon distribution of the tfirst solvent solution in a second solvent in which the first solvent is miscible, the polymer is soluble and the solid material is insoluble and effecting separation of the resultant precipitant from the remainder of the mixture where so desired for further employment of the solid material.

Specifically, the preferred dye image-forming mate-. rials, i.e., dye developers, such as those detailed in a plurality of US patents cited herein as, for example, the cyan dye developer the magenta dye developer and the yellow dye developer HO-CHz-CH: Q

iIZUCHa O lCHr-CH the range of processing pH and which at the pH at which the selected dye is substantially insoluble is adapted to inhibit particle growth during precipitation of the dye at that pH; adjusting the pH of the medium to a pH at which the dye is substantially insoluble, and separating the resultant dye from the medium.

As examples of polymers which are souble in an aqueous medium over a broad range of pH values and specifi cally adapted for employment in the process detailed above, mention may bemade of, for example, synthetic vinyl polymers such as poly(vinylbenzyltrimethyl am monium chloride), polyvinyl alcohol, polyvinyl pyrrolidone, polystyrene sulfonate, polyethylene maleic anhydride, etc.; cellulosic polymers such as hydroxyethyl cellulose, carboxymethyl cellulose, etc.; naturallyioccurring polymers such as gelatin, etc.; and the like.

In general, it is understood that during precipitation .of dye from the medium that polymer interacts with the surface of thesolid dye particles forming in themedium to prevent secondary particle growth probably as a function of decreased; soluble dye ion concentration contiguous reactive surface sites of dye particle, and in part may be found to cop'recipitate with dye particles contiguous and bound to a surface of such particles.

It will be recognized that in accordance with the present invention a multiplicity of polymers are readily available in the art which exhibit solubility in, for example, both water and various organic solvents and exhibit the desired grain growth modulating properties which may be illustrated by reference to the aforementioned polyvinyl pyrrolidone which is soluble in water and in the following named organic materials in a ratio of at' least one" part PVP to ninety parts solvent: chlorinated.hydrocarbons, such as methylene dichloride,"chloroform, ethylenedichloride; alcohols, such a methyl alcohol,"ethyl alcohol, propyl alcohol, isopropyl alcohol,-butyl alcohol, sec butyl alcohol, isobutyl alcohol, amyl alcohol, 2-ethyl-1-hexanol, cyclohexanol, phenolyethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, glycerol; ether-alcohols, such as diethylene glycol, triethylene glycol,'hexaethylene glycol, polyethylene glycol; thioether-alcohol, such as 2,2 thiodiethanol; ketone, such as methylcyclohexanone; ketone-alcohol, such as diacetone alcohol; ester-alcohol, such as ethyl lactate; nitroparaflins, such as nitromethane, nitroethane; amines, such as butylamine, cyclohexylamine, aniline, ethylenediamine, pyridine, morpholine, 2-aminoethanol, diethanolamine, triethanolamine, aminoethylethanolamine, hydroxyethylmorpholine, 2 amino 2- methyl-l-propanol; acids, such as formic acid, acetic acid, propionic acid; and lactone, such as -butyrolactone.

It will be apparent that either the aqueous medium and any one or more of the organic media or any combination of organic solvents may comprise either the first or the second solvent in accordance with the respective solubilities of the dye image-providing material elected to be dispersed and that the polymer elected may be empirically selected on the basis of its availability, economics and its effective capacity to render seed grain surface sites ineffective with respect to grain growth by accretion beyond the lower limit of the tyndall effect or about one-fourth of a wavelength of light.

The photosensitive silver halide layers employed for the fabrication of the photographic film unit maybe prepared by reacting a water-soluble silver salt, such as silver nitrate, with at least one water-soluble halide, such as ammonium, potassium or sodium chloride, together with corresponding iodide and bromide, or ammonium, potassium or sodium bromide, together with corresponding iodide, in an aqueous solution of a peptizing agent such as colloidal gelatin solution; digesting the dispersion at an elevated temperature, to provide increased crystal growth; washing the resultant dispersion to remove undesirable reaction products and residual water-soluble salts, for example, employing the preferred gelatin matrix material, by chilling the dispersion, noodling the set dispersion, and washing the noodles with cold water, or, alternatively, employing any of the various floc systems, or procedures, adapted to effect removal of undesired components, for example, the procedures described in US. Pats. Nos. 2,614,928; 2,614,929; 2,728,662, and the like; afterripening the dispersion at an elevated'tempera ture in combination with the addition of gelatin or such other polymeric material as may be desired and various adjuncts, for example, chemical sensitizing agents of U5. Pats. Nos. 1,574,944; 1,623,499; 2,410,689; 2,597,856; 2,597,915; 2,487,850; 2,518,698; 2,521,926; and the like; all according to the traditional procedures of the art, as described in Neblette, C. B., Photography: Its Materials and Processes, 6th Ed., 1962. 7

Optical sensitization of the emulsions silver halide crystals may be accomplished by contact of the emulsion composition with an effective concentration ofthe selected optical sensitizing dyes dissolved in an appropriate dis persing solvent such as methanol, ethanol, acetone,water, and the like; all according to the traditional procedures of the art, as described in Hammer, F. M., The Cyanine Dyes and Related Compounds.

Additional optional additives, such as coating aids, hardeners, viscosity-modifying agents, stabilizers, preservatives, and the like, for example, those set forth hereinafter, also may be incorporated in the emulsion formulation, according to the conventional procedures known i the photographic emulsion manufacturing art.

As the binder for the photoresponsive material, the aforementioned gelatin may be, in whole or in part, replaced with some other natural and/0r synthetic processiodochlorobromide,

9;" ingcompositionpermeable-polymeric material such as albumin; casein; or 'z'ei'n or resins suchas cellulosederivativef'as described in' "US. Pats. Nos. 2,322,085 and 2,541,474;-vinyl'polymers such 'asde'scribed in an extensivemultiplicityof readily available U.S. and foreign patents or the photoresponsivematerial may-be present substantially free of'inter'stitial binding agent as described in U.S. Patsi Nos. 2,945,77l;-3,145,566; 3,142,567; Newman} Comment on Non-Gelatin Film, B. I. O. P., 434, Sept. 15, 1961; and Belgian Pats. Nos. 642,557 and 642,558.

'-'One procedure particularly useful for the production of preferred polydisperse g'elatino silver iodohalide emulsions comprises the-formulation, for example, in the manner previously detailed, of'a silver iodohalide emulsion by initially forming the emulsion, separating from the formulation undesired reaction products, afterripening the resultant silver iodohalide emulsion in combination with the'selected auxiliary sensitizing, speed increasing, etc., adjuncts elected, and separating from the emulsion formulation about 15 to 30 percent of the silver halide grains possessing the greatest and/or least mass.

Specifically, a preferred silver iodobromide emulsion may be readily formulated by a conventional single jet addition, over a period of 40 minutes, at a rate of 10 liters per minute from the jet, a solution comprising 3 M. silver nitrate, in distilled water, at room temperature, into a solution comprising 3 M. alkali halide (e.g. potassium) possessing 98% bromide and 2% iodide in trimellitic acid anhydride derivatized acid pig gelatin, at room temperature, preadjusted to pH 6 with sodium hydroxide. Theresultant silver iodobromide emulsion is held subsequent to formulation for the period of time required to provide the selected silver halide grain size distribution and separation of the silver iodobromidetrimellitic acid anhydride derivatized gelatin precipitate provided by the addition of 2 N. sulfuric acid to the reaction mixture. The resultant precipitate is washed with 'chilled distilled Water until the wash water exhibits a conductivity of about 300 to 500 microm hos/cm, the volume adjusted with distilled water for the addition of 100 gms. of lime bone gelatin per 1000 cc. of emulsion, chemically sensitized at about 56 C., pH 5 and pAg 9, by the addition of a sensitizing amount of a solution containing-0.1 gram of ammonium thiocyanate in 9.9 cc. of water-and 1.2 cc. of a solution containing 0.097 gram of gold chloride in 9.9 cc. of water, and a 0.02% aqueous sodium thiosulfate solution optimized for the mean silver ,halide iodide crystal concentration, and the emulsion then afterripening for three hours at a temperature of 60 C. and a pH of 5.5.

-In preferred embodiments of the present invention, the photosensitive silver iodochlorobromide, iodochloride and/or iodobromide emulsions employed will be emulsions adapted to provide a Diffusion Transfer Process Exposure Index about 50, which Index indicates the correct exposure rating of a diffusion transfer color process at which an exposure meter, calibrated to the ASA Exposure Index, mustbe set in order that it give correct exposure data for producing color transfer prints of satisfactorily high quality. The Dilfusion Transfer iProcess Exposure Index is based on a characteristic H & D curve relating original exposure of the photosensitive silver iodochloride and/or iodobromide emulsion to the respective curve densities forming the resultant transfer image. Thus, the Diffusion Transfer Exposure Index is based on the exposure to which the polydisperse silver iodochlorobromide, iodochloride and/or iodobromide emulsion, for use in color diffusion transfer processes, must be subjected in order to obtain an acceptable color transferimage by that process and is a direct guide to the exposure setting to be entered in a camera in order to obtain proper exposure of the film unit. l

In a'preferred' embodiment of the present invention, the means for inter-posing the processingcomposition selected intermediate the receptionlayer and the silver halidelayer'comprises a-rupturable container retaining a processing composition comprising .the solvent-andp'H concentrations required fixedly positioned and extending transverse a leading edge of the 'film .unit to effect, upon application of compressive pressure, discharge of the processing composition intermediate the reception layer and the photosensitive silver iodochlorobromide layer next adjacent. In such embodiment the opacifying agent is preferably disposed within the processing composition, as retained in the rupturable container, for distribution as a component of such composition intermediate the reception and silver halide layers, subsequent to selective exposure of the film unit.

Multicolor images may be obtained using color imageforming components in the diffusion transfer process of the present invention by several techniques. One such technique contemplates obtaining multicolor transfer images utilizing, for example, dye developers as dye imageproviding materials by employment of an integral multilayer photosensitive element, such as is disclosed in aforementioned U.S. Patent No. 3,415,644 wherein at least two selectively sensitized photosensitive strata, superposed on a single support, are processed, simultaneously and without separation, with a single, common image-receiving layer. A suitable arrangement of this type comprises the opaque support carrying a red-sensitive silver iodochlorobromide, iodochloride and/ or iodobromide stratum, a green-sensitive silver iodochlorobromide, iodochloride and/or iodobromide stratum and a blue-sensitive silver iodochlorobromide, iodochloride and/or iodobromide stratum, said emulsions having associated therewith, respectively, for example, a cyan dye developer, a magenta dye developer and a yellow dye developer. The dye developer may be utilized in the silver iodochlorobromide, iodochloride and/or iodobromide stratum, for example, in the form of the solid dispersion formats of the present invention, or it may be employed as a layer behind the appropriate silver iodochlorobromide, iodochloride and/ or iodobromide strata. Each set of silver iodochlorobromide, iodochloride and/ or iodobromide strata and associated dye developer strata are disclosed to be optionally separated from other sets by suitable interlayers, for ex ample, by a layer of gelatin or polyvinyl alcohol. In certain instances, it may be desirable to incorporate a yellow filter in front of the green-sensitive emulsion and such yellow filter may be incorported in an interlayer. However, where desirable, a yellow dye developer of the appropriate spectral characteristics and present in a state capable of functioning as a yellow filter may be employed. In such instances, a separate yellow filter may be omitted.

In a preferred embodiment of the present invention, the film unit is specifically adapted to provide for the production of a multicolor dye transfer image and the photosensitive laminate comprises, in order of essential layers, the dimensionally stable opaque layer; at least two selectively sensitized silver iodochlorobromide, iodochloride and/ or iodobromide strata each having dye image-providing material of predetermined color associated therewith, for example, dye developers as detailed above, which are soluble and diffusible in processing composition as a function of the point-to-point degree of exposure of the respective associated silver iodochlorobromide, iodochloride and/ or iodobromide stratum; a polymeric layer dyeable by the dye image-providing materials; and a dimensionally stable transport layer.

hereinafter employing the last-mentioned preferred structural embodiment, without limitation of the invention to the preferred structure denoted, 'fi'The dye developers, as noted above, are compounds which contain, in the same molecule, both the chromophoric system of a dye and also a silver halide developing function. By a silver halide developing function is meant a grouping adapted to develop exposed silver halide. A preferred silver halide development function is a hydroquinonyl group. Other suitable developing functions include ortho-dihydroxyphenyl and orthoand para-amino substituted hydroxyphenyl groups. In general, the development function includes a benzenoid developing function, that is, an aromatic developing group whichforms quinonoid or quinone substances which oxidized.

The dye developers are preferably selected for their ability to provide colors that are useful in carrying out subtractive color photography, that is, the previously mentioned cyan, magenta and yellow. The dye developers employed may be incorporated in the respective silver halide emulsion or, in the preferred embodiment, in a separate layer behind the respective silver halide stratum. Specifically, the dye developer may, for example, be in a coating or layer behind the respective silver halide stratum and such a layer of dye developer may be applied by use of a coating composition containing about 0.5 to 8%, by weight, of the respective dye developer distributed in a film-forming natural, or synthetic, polymer, for example, gelatin, polyvinyl alcohol, and the like, adapted to be permeated by the chosen diffusion transfer fluid processing composition.

An extensive compilation of specific dye developers particularly adapted for employment in photographic diffution transfer processes is set forth in U.S. Patent No.

2,983,606 and in the various copending U.S. applications referred to in that patent, especially in the table of U.S. applications incorporated by reference into the patent as detailed in Column 27. As examples of additional U.S. patents detailing specific dye developers for photographic transfer process use, mention may also be made of U.S. Pats. Nos. 2,983,605; 2,992,106; 3,047,386; 3,076,808; 3,076,820; 3,077,402; 3,126,280; 3,131,061; 3,134,762; 3,134,765; 3,135,604; 3,135,605; 3,135,606; 3,135,734; 3,141,722; 3,142,565; and the like.

The polydisperse silver iodochlorobromide, iodochloride and/or iodobromide strata comprising the multicolor photosensive laminate preferably possess predominant spectral sensitivity to separate regions of the spectrum and each has associated therewith a dye which is a silver halide developing agent and is, most preferably, substantially soluble in the reduced form only at a first pH possessing, subsequent to processing, a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion.

In the preferred embodiment, each of the silver halide strata, and its associated dye, is separated from the remaining strata, and their associated dye, by separate alkaline solution permeable polymeric interlayers.

In such preferred embodiment of the invention, the silver halide strata comprises photosensitive silver iodochlorobromide and/or iodobromide dispersed in gelatin and are about 0.6 to 6 microns in thickness; the dye itself is dispersed in an aqueous alkaline solution polymeric binder, preferably gelatin, as a separate layer about 1 to 7 microns in thickness; the alkaline solution permeable polymeric interlayers, preferably gelatin, are about 1 to microns in thickness; the dyeable polymeric layer is transparent and about 0.25 to 0.4 mil in thickness; and each of the dimensionally stable opaque and transparent layers are alkaline solution impermeable, processing composition vapor permeable and about 2 to 6 mils in thickness. It will be specifically recognized that the relative dimensions recited above may be appropriately modified, in accordance with the desires of the operator, with respect to the specific product to be ultimately prepared.

Although in oneembodiment of the present invention, the dimensionally stable layers employed inthe practice of the invention may possess a vapor transmission rate of 1 or less guts/24 hrs./'in. /mil, in a preferred embodi ment of the invention, the layers employed will possess a vapor transmission rate for the selected processing compo sition solvent averaging not less than about 100.gms./2 4 hrs/100 infi/mil, most preferablyin terms of the preferred solvent, water, a vapor transmission rate averaging in excess of about 300 gms. of water/24 hrs./100in. /rr 1il, and may advantageously comprise a microporous polymeric film possessing a pore distribution which does not unduly interfere with the dimensionally stability of the layers or, where required, the optical characteristics of such. layers. Such pore distribution may comprise, for example, an average pore diameter of from about 20 microns to about 100 microns and a pore volume of about 3 percent to about 7 percent.

In a particularly preferred embodiment of the present invention, the preferred solvent, water, may be employed in a weight/weight ratio of about 1:10 to 1:20 dye to to comprise about 300 to 1300 mg.s./ft. liquid permeable polymeric binder material, about 200 to 400 mgs./ft. dye to comprise about 300 to 1300 mgs./ft liquid permeable polymeric binder material, about 200 to 400 mgs./ft. dye and about 5000 mgs./ft. water.

The preferred dimensionally stable layers are designed so that there is no liquid flow through the layers while allowing the vapor of the processing composition solvent to pass by diffusion from the evaporating liquid body and the operational efficiency of the film unit is directly dependent upon the nature and quality of the vapor permeable membrane characteristics of the layers selected. The vapor transmission characteristics desired are directed to maximization of the rate at which the required quantity of processing solvent is effectively evacuted from the film unit subsequent to substantial dye transfer image formation by diffusion transfer processing, commensurate with maintaining the liquid impermeability and dimensional stability characteristics of the layers. Thus, the layers should possess the maximum vapor transmission capacity which permits the passage of processing composition solvent vapor, and any gas dissolved therein, at its vapor pressure, without allowing passage of fluid processing composition. The layers employed in accordance with=the present invention therefore should be as thin as possible for solvent vapor transmission efficiency yet retainsufficient strength to provide stability to and resist chemical and physical degradation of the film unit under conditions of use. e

In the preferred embodiment of the present inventions film unit for the production of a multicolor transfer image, the respective silver halide/dye developer units of the photosensitive element will be in the form of a tripa'ck configuration which will ordinarily comprise a cyan dye developer/red-sensitive emulsion unit contiguous the dimensionally stable opaque layer, the yellow dye developer/ blue-sensitive emulsion unit most distant from the opaque layer and the magenta dye developer/green-sensitive ernul sion unit intermediate those units, recognizing that the relative order of such units may be varied-in accordance with the desires of the operator.

Reference is now made to FIGS. 1 through 7 of the drawings wherein there is illustrated a preferred film unit of the present invention and wherein like numbers, appearing in the various figures, refer to like components.

As illustrated in the drawings, FIG. 1 sets forth a perspective view of the film unit, designated 10, and each of FIGS. 2 through 7 illustrate diagrammatic cross-sectional views of film unit 10, along the stated section lines 2-2, 3-3, 55 and 7-7, during the various depicted stages in the performance of a photographic diffusion transfer process as detailed hereinafter. I

Film unit 10 comprises rupturable containerll, retaining, prior to processing, aqueous processing composition 1mm photosensitive laminate 13 including, in order, dimensionally'fstable opaque layer 14, preferably an actinic radiation-opaque flexible sheet material; cyan dye developer layer 15; red-sensitive silver iodochlorobromide, iodochloride and/ or iodobromide emulsion layer 16 possessing the parameters denoted above; interlayer 17; magenta dyedeveloper layer 18; green-sensitive silver iodochlorobromide, iodochloride and/or iodobromide emulsion :layer 19 possessing the parameters denoted above"; interla'ye'r 20; yellow dye developer layer 21; bluesensitive silver iodochlorobromide, iodochloride and/or iodobromide emulsion layer 22 possessing the parameters denoted above; auxiliary layer 23, which may contain an silver halide developing agent; image-receiving layer 24; spacer layer 25; neutralizing layer 26; and dimensionally stable transparent layer 27, preferably an actinic radiation transmissive flexible sheet material.

The structural integrity of laminate 13 may be maintained, at least in part, by the adhesive capacity exhibited between the various layers comprising the laminate at their opposed surfaces. However, the adhesive capacity exhibited at an" interface intermediate image-receiving layer 24 and the silver iodochlorobromide, iodochloride and/ or iodobromide emulsion layer next adjacent thereto, for example, image-receiving layer 24 and auxiliary layer 23 as illustrated in FIGS. 2 through 7, should be less than that exhibited at the interface between the opposed surfaces of the remainder of the layers forming the laminate, in order to facilitate distribution of processing solution 12 intermediate the stated image-receiving layer 24 and the silver iodochlorobromide, iodochloride and/or iodobromide emulsion layer next adjacent thereto. The laminates structural integrity may also be enhanced or provided, whole or in part, by providing a binding member extending around, for example, the edges of laminate 13, and maintaining the layers comprising the laminate intact, except at the interface between layers 23 and 24 during distribution of processing composition 12 intermediate those layers. As illustrated in the figures, the binding member may comprise a pressure-sensitive tape 28 securing and/or maintainingthe layers oflaminate 13 together at itsrespective edges. Tape 28 will also act to maintain processing solution 12 intermediate image-receiving layer 24 and the silver iodochlorobromide, iodochloride and/or iodobromide emulsion layer next adjacent thereto, upon application of compressive pressure to pod 11 and distribution of its contents intermediate the stated layers. Under such circumstances, binder tape 28 will act to prevent leakage of fluid processing composition from the film units laminate during and subsequent to photographic processing.

Rupturable container 11 may be of the type shown and described in any of US. Pats. Nos. 2,543,181; 2,634,886; 3,653,732; 2,723,051; 3,056,492; 3,056,491; 3,152,515; and

.the like. In general, such containers will comprise a rectangular blank of fluidand air-impervious sheet material folded longitudinally upon itself to form two walls 29 which are sealed to one another along their longitudinal and end margins to form a cavity in which processing composition 12 is retained.- The longitudinal marginal seal 30 is made weaker than the end seals 31 so as to become unsealed in response to the hydraulic pressure generated within the fluid contents 12 of the container by the application of compressive pressure to walls 29 of the container. 'As illustrated in FIGS. 1, 2 and 3, container 11 is fixedly positioned and extends transverse a leading edge of photosensitive laminate 13 whereby to effect unidirectional discharge of the containers content 12 between image-receiving layer 24 and the stated layer next adedge of lamine 13 with its longitudinal marginal seal 30 directed toward the interface between image-receiving layer 24 and auxiliary layer 23. As shown in FIGS. 1, 2

and 4, container 11 is fixedly secured'to laminate 13 by extension 32 of tape 28 extending over a portion of one wall 29 of the container, in combination with a separate retaining member such as illustrated retainingtape 33 extending over a portion of laminate'13s surface generally equal in area to about that covered by'tape'28.

As illustrated in FIGS. 1, 2 and 4, extension flap 32 of tape 28 is preferably of such area' and dimensions that upon, for example, manual separation of container 11 and'tape 33, subsequent to distributionof processing composition 12, from the remainder of film unit 10, flap 32 may be folded over the edge of laminate 13, previously covered by tape 33, in order to facilitate maintenance of the laminates structural integrity, for example, during the flexations inevitable in storage and use of the processed film unit, and to provide a suitable mask or frame, for viewing of the transfer image through the picture viewing area of transparent layer 27.

The fluid contents of the container preferably comprise an aqueous alkaline solution having a pH and solvent concentration at which the dye developers are soluble and diffusible and contains inorganic light-reflecting pigment and at least one optical filter agent at a pH above the pKa of such agent in a quantity suflicient, upon distribution, effective to provide a layer exhibiting optical transmission density about 6.0 and optical reflection density about 1.0 to prevent exposure of photosensitive silver iodochlorobromide, iodochloride and/or iodobromide emulsion layers 16, 19 and 22 by actinic radiation incident on dimensionally stable transparent layer 27 during processing in the presence of such radiation and to afford immediate viewing of dye image formation in image-receiving layer 24 during and subsequent to dye transfer image formation. Accordingly, the film unit may be processed, subsequent to distribution of the composition, in the presence of such radiation, in view of the fact that the silver iodochlorobromide, iodochloride and/ or iodobromide emulsion or emulsions of laminate are appropriately protected by incident radiation, at one major surface of the opaque processing composition and at the remaining major surface by the dimensionally stable opaque layer. If the illustrated binder tapes are also opaque, edge leakage of actinic radiation incident on the emulsion or emulsions will also be prevented.

The selected reflecting pigment should be one providing a background suitable for viewing the dye developer transfer image formed in the dyeable polymeric layer. In general, while substantially any reflecting agent may be employed, it is preferred that a reflecting agent be selected that will not interfere with the color integrity of the dye transfer image, as viewed by the observer, and, most preferably, an agent which is aesthetically pleasing to the viewer and does not provide a background noise signal degrading, or detracting from, the information content of the image. Particularly desirable reflecting agents will be those providing a white background, for viewing the transfer image, and specifically those conventionally employed to provide background for reflection photographic prints and, especially those agents possessing the optical properties desired for reflection of incident radiation.

As examples of reflecting pigments adapted for employment in' the practice of the present'invention, mention may be made of barium sulfate, zinc sulfide, titanium dioxide, barium stearate, silver flake, silicates, alumina,

zirconium oxid'e, zirconium acetyl acetate, sodium zircon ium sulfate, kaolin, mica, and the like. I

A particularly preferred reflecting agent comprises titanium dioxide due toits highly effective reflection properties. In general, in such preferred embodiment, based upon percent titanium dioxide (weight/volume) a processing composition containing about 1500 to 4000 mgs./ ft. titanium dioxide dispersed in 100 cc. of water will provide a percent reflectance of about to percent. In the most preferred embodiments, the percent reflec- 15 tance particularly desired willbe in the order of about 85 -percent. 1

In embodiments wherein the dispersion comprises a preformed layer positioned intermediate the reception layer and next adjacent silver iodochlorobromide, iodo: choloride and/or iodobromide layer, the pigment layer will be sufficiently transparent to allow transit of exposing radiation through the pigment layer and may comprise titanium dioxide reflecting agent possessing a particle size distribution averaging about 0.2 micron in diameter and preferably about 0.05 micron in diameter as initially present preceding exposure of the film unit, which preferred materials, upon contact with aqueous alkaline processing composition, preferably aggregate to provide particlespossessing a diameter about 0.2 micron in diameter and will be coated at a coverage of about 200 to 1000 mgs./ft. Specifically, the reflecting agent will be present in a quantity insufficient to prevent exposure of the emulsion layers by actinic radiation incident on the dimensionally stable transparent layer of the film unit but in a concentration suflicient, subsequent to processing, to mask dye developer associated with the silver iodochlorobromide, iodochloride and/or iodobromide emulsion strata from the dye transfer image. In the preferred construction of such embodiment, the pigment such as titanium dioxide will be initially present in a relatively small particle size to provide unexpectedly efficient transit of radiation through the reflecting layer during exposure which upon contact with an alkaline processing composition and aggregation of the pigment particles provides efficient light reflectivity and masking capacity subsequent to such aggregation.

In general, the reflecting agents to be employed are those which remain substantially immobile Within their respective compositions during and subsequent to photographic processing and particularly those which comprise insoluble and nondiffusible inorganic pigment dispersions within the layer in which they are disposed.

Where desired, reflecting agent pigment may thus be distributed in whole or in part within a processing com position permeable polymeric matrix such as gelatin and/ or any other such polymeric matrixes as are specifically denoted throughout the specification as suitable for employment as a matrix binder and may be distributed in one or more of the film unit layers which may be separated or contiguous, intermediate the image-receiving layer and next adjacent silver iodochlorobromide, iodochloride and/ or iodobromide layer, provided that its distribution and concentration is effective to provide the denoted post processing masking function, and/or in whole or in part the reflecting agent may be ultimately disposed within the processing composition residuum located intermediate the image-receiving layer and next adjacent silver iodochlorobromide, iodochloride and/ or iodobromide emulsion strata and associated dye image-forming material.

The optical filter agent elected should be one exhibiting, at a pH above its pKa, maximum spectral absorption of radiation at the wavelengths to which the film units photosensitive silver iodochlorobromide, iodochloride and/or iodobromide layer or layers are sensitive and should be substantially immobile or nondiffusible Within the pigment dispersion, during performance of its radiation filtration function, in order to maintain and enhance theoptical integrity of the dispersion as a radiation filter unit functioning in accordance with the present invention, and to prevent its diffusion into and localized concentration within the image-receiving layer thereby decreasing the efliciency of the reflecting pigment dispersion as a background against which image formation may be immediately viewed, during the initial stages in the diffusion transfer processing of the film unit, by filter agent absorption of dispersion reflected visible radiation prior to reduction in the environmental pH below the pKa of the agent. Commensurate with the spectral sensitivity range of the associated silver halide layer or layers, the optical filter agent selected may comprise one or more filterdyes possessing absorption complementary to such s'ilveriodochlo irjo" mide layers in order to provide effective protection again t physical fog providing radiation during processing; Recog nizing that the filter agent absorption will derogate', from image-viewing characteristics by contaminating reflecting pigment background, the selected agents should be those exhibiting major spectral absorption at the pH at which processing is effected and minimal absorption at a' pH below that which obtains during transfer image formation; Accordingly, the selected optical filter agent or agents should possess a pKa below that of the processing pHan'd above that of the environmental pH subsequent to transfer image formation. and will be preferably selected for employment in the minimum concentrationnece ssary to provide an optical transmission density "about'6.0," at wavelengths at which the silver iodochlorobromide layer maximally responsive, and an optical reflection density about 1.0 at such wavelengths. a

As specific examples of such pH-sensitive optical filter agents adapted for employment in the practice of the present invention, reference is directed to the agents set forth in aforementioned US. Pat. No. 3,647,437, incor porated therein by reference. p

In general, preferred agents, both opacifying and filter, are those which remain immobile within their respec tive compositions during and subsequent to photographic processing and particularly those which comprise insoluble and nondiifusible materials. 7

As disclosed in the previously cited patents, the liquid processing composition referred to for effecting multicolor diffusion transfer processes comprises at least an aqueous solution of an alkaline material, for example, diethyl amine, sodium hydroxide or sodium carbonatehnd'the like, and preferably possessing a pH in excess of 12 and most preferably includes a viscosity-increasing compound constituting a film-forming material of the type'which; when the composition is spread and dried, forms a rela tively firm and relatively stable film; The preferred film forming materials disclosed comprise high molecular weight polymers such as polymeric, water-soluble ethers which are inert to an alkaline solution such 'as,'for example, hydroxyethyl cellulose or sodium carboxymethyl cellulose. Additionally, film-forming materials or thickening agents whose ability to increase viscosity is substantially unaffected if left in solution for a long period of time are also disclosed to be capable of utilization. As stated, the film-forming material is preferably contained-in the processing composition in such suitable'quantities as to-impart to the composition a viscosity in excess of cps. at a temperature of approximately 24 C. and preferably in the order of 100,000 cps. to 200,000 cps. at that temperature.

In the performance of a diffusion transfer multicolor process employing film unit 10, the unit is'exposed to radiation, actinic to photosensitive laminate 13, incident on the laminates exposure surface, as illustrated in FIG. 3

Subsequent to exposure, as illustrated by FIGS. 2 and 4, film unit 10 is processed by being passed through-opposed suitably gapped rolls 35 in order to apply compressive pressure to frangible container 11 and to effect rupture of longitudinal seal 30 and distribution of alkaline processing composition 12, possessing inorganic light-reflecting pigment and optical filter agent at a pH .abovethe pKa of the filter agent and a pH at which the cyan, magenta and yellow dye developers are soluble and difl'usible as a function of the point-to-point degree of :exposure of red-sensitive silver iodochlorobromide, iodochloride and! or iodobromide emulsion layer .16, green-sensitive silver iodochlorobromide, iodochloride I and/or iodobromide emulsion layer 19 and blue-sensitive silver iodochlorobromide, iodochloride and/ or iodobromide emulsion layer 22, respectively, intermediate image-receiving layer 24. and auxiliary layer 23.

Alkaline process-ing composition 12 permeates emulsion layers 16, 19 and 22 to initiate development of the latent images contained in the respective emulsions. The cyan, magenta and yellow dye developers, of layers 15, 18 and 21, are immobilized as a function of the development of their respective associated silver iodochlorobromide, iodochloride and/or iodobromide emulsions, preferably substantially as a result of their conversion from the reduced form to their relatively insoluble and nondiffusible oxidized form, thereby providing imagewise distributions of mobile, soluble and diffusible cyan, magenta and yellow dye developer, as a function of the point-topoint degree of their associated emulsions exposure. At least part of the imagewise distributions of mobile cyan, magenta and yellow dye developer transfers, by diffusion, to dyeable polymeric layer 24 to provide a multicolor dye transfer image to that layer which is viewable against the background provided by the reflecting pigment present in processing composition residuum 12 masking cyan, magenta and yellow dye developer remaining associated with blue-sensitive emulsion layer 22, green-sensitive emulsion layer 19 and red-sensitve emulsion layer 16. Subsequent to substantial transfer image formation, a sufticient portion of the ions comprising aqueous alkaline processing composition 12 transfer, by diffusion, through permeable polymeric reception layer 24, permeable spacer layer 25 to polymeric neutralizing layer 26 whereby the environmental pH of the system decreases as a function of neutralization to a pH at which the cyan, magenta and yellow dye developers, in the reduced form, are substantially nondifiusible to thereby provide a stable multicolor dye transfer image and discharge of the pH-sensitive optical filter agent by reduction of the pH substantially below the pKa of such agent to thereby provide maximum reflectivity in terms of the pigment concentration present.

The alkaline solution component of the processing composition, positioned intermediate the photosensitive element and the image-receiving layer, thus permeates the emulsions to initiate development of the latent images contained therein. The respective associated dye developers are mobilized in unexposed areas as a consequence of the development of the latent images. This mobilization is apparently, at least in part, due to a change in the solubility characteristics of dye developer upon oxidation and especially as regards its solubility in alkaline solutions. It may also be due in part to a tanning effect on the emulsion by oxidized developing agent, and in part to a localized exhaustion of alkali as a result of development. In unexposed and partially exposed areas of the emulsions, the associated dye developer is diffusible and thus provides an imagewise distribution of unoxidized dye developer dissolved in the liquid processing composition, as a function of the poin-t-to-point degree of exposure of the silver iodochlorobromide, iodochlorode and/or iodobromide emulsion. At least part of this im agewise distribution of unoxidized dye developer is transferred, by imbibition, to a superposed image-receiving layer or element, said transfer substantially excluding oxidized dye developer. The image-receiving element receives a depthwise diffusion, from the developed emulsion, of unoxidized dye developer without appreciably disturbing the imagewise distribution thereof to provide the reversed or positive color image of the developed image.

Subsequent to distribution of processing composition 12, container 11 may be manually dissociated from the remainder of the film unit, as described above, to provide the product illustrated in FIG. 6.

The present invention will be further illustrated and detailed in conjunction with the following illustrative constructions which set out representative embodiments and photographic utilization of the novel photographic film units of this invention, which, however, are not limited to the details therein set forth and are intended to be illustrative only.

Film units similar to that shown in the drawings may be prepared, for example, by coating, in succession, on a 5 mil opaque polyester film base, the following layers:

1. a layer comprising a solid dispersion of the cyan dye developer of Formula I prepared by (a) dissolving 4 grams of dye in 200 cc. of 1.7 M potassium hydroxide and 36 cc. of a 33 percent solution of poly(vinylbenzyl trimethyl ammonium chloride) in water under nitrw gen, (b) reducing the pH of the solution to about 1 by the addition of 40 cc. of hydrochloric acid, (0) dialyzing the resultant dispersion to about pH 5, and '(d) dispersing the dialyzed dispersion in gelatin to provide a coating coverage of about 98 mgs./ft. of dye and about 92 mgs./ft. of gelatin;

2. a red-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 140 mgs./ft. of silver and about 27 mgs./ft. of gelatin;

3. a layer of butyl acrylate/diacetone acrylamide/ styrene/methacrylic acid (60/30/ 4/ 6) and polyacrylamide coated in a ratio of about 29:1, respectively, at a coverage of about mgs./ft.

4. a layer comprising a solid dispersion of the magenta dye developer of Formula 11 prepared by (a) dissolving 4 grams of dye in 200 cc. of 1.7 M potassium hydroxide and 36 cc. of a 33 percent solution of poly(vinylbenzyl trimethyl ammonium chloride) in water under nitrogen, (b) reducing the pH of the solution to about 1 by the addition of 40 cc. of hydrochloric acid, (c) dialyzing the resultant dispersion of about pH 5, and (d) dispersing the dialyzed dispersion in gelatin to provide a coating coverage of about 71 mgs/ftfl of dye and about 50 mgs./ft. of gelatin;

'5. a green-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 80 mgs/tt. of silver and about 40 mgs./-ft. of gelatin;

6. a layer of butyl acrylate/diacetone acrylamide/ styrene/methacrylic acid (60/30/4/6) and polyacrylamide coated in a ratio of about 29:4, respectively, at a coverage of about 60 mgs./ft.

7. a layer comprising a solid dispersion of the yellow dye developer of Formula III prepared by (a) dissolving 4 grams of dye in 200 cc. of 1.7 M potassium hydroxide and 36 cc. of a 33 percent solution of poly(vinylbenzyl trimethyl ammonium chloride) in water under nitrogen, (b) reducing the pH of the solution to about 1 by the addition of 40 cc. of hydrochloric acid, (c) dialyzing the resultant dispersion to about pH 5, and (d) dispersing the dialyzed dispersion in gelatin to provide a coating coverage of about 81 mgs./ft. of dye and about 54 mgs./ft. of gelatin and including auxiliary developer 4'-methylphenyl hydroquinone at a coverage of about 15 mgs/tt. of auxiliary developer;

8. a blue-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 65 mgs./ft. of silver and about 33 mgs/ft of gelatin; and

9. a layer of gelatin coated at a coverage of about 45 mgs./ft. of gelatin.

A transparent 5 mil polyethylene terephthalate film base may be coated, in succession, with the following illustrative layers:

1. the partial butyl ester of polyethylene/maleic anhydride copolymer prepared by refluxing, for 14 hours, 300 grams of high viscosity poly-(ethylene/maleic anhydride), 140 grams of n-butyl alcohol and 1 cc. of 85 percent phosphoric acid to provide a polymeric acid layer at a coverage of about 2500 mgs./ft.

2. a timing layer containing about a 40:1 ratio of a 60/ 30/ 4/ 6 copolymer of butylacrylate, diacetone acrylamide, styrene and methacrylic acid and polyacrylamide at coverage of about 500 mgs./ft. and

3. a 2:1 mixture, by weight, of polyvinyl alcohol and poly-4-vinylpyridine, at a coverage of about 400 mgs./ ft. to provide a polymeric image-receiving layer containing development restrainer.

The two components thus prepared may then be taped together in laminate form, at their respective edges, by means of a pressure-sensitive binding tape extending around, in contact with, and over the edges of the resultant laminate.

A rupturable container comprising an outer layer of lead foil and an inner liner or layer of polyvinyl chloride retaining an aqueous alkaline processing solution such as, for example, the processing compositions specifically detailed in copending U.S. application Ser. No. 246,669, filed Apr. 24, 1972, and which compositions may include, per 100 cc. of water, about 4.7 grams of KOH, about 0.8 gram of carboxymethyl cellulose, about 42 grams of TiO about 1.3 grams of N-benzyl-u-picolinium bromide, about 0.7 gram of N-phenethyl-a-picolinium bromide, about 2 grams of an aqueous silica dispersion comprising about percent SiO and one or more antifoggants such as about 0.6 gram of benzotriazole and about 0.03 gram of 6-methyl 5 bromo-4-azabenzimiclazole, together with such other processing composition adjuvants, for example, those adjuvants specifically identified in the last-cited application, as the operator shall optionally select, may then be fixedly mounted on the leading edge of each of the laminates, by pressure-sensitive tapes interconnecting the respective containers and laminates, such that, upon application of compressive pressure to the container, its contents may be distributed, upon rupture of the containers marginal seal, between the polymeric image-receiving layer and next adjacent gelatin layer.

The photosensitive composite film units may be exposed through radiation incident on the transparent polyester film base and processed by passage of the exposed film units through appropriate pressure-applying members, such as suitably gapped, opposed rolls, to effect rupture of the container and distribution of its contents. Subsequent to processing, the multicolor dye transfer image formation may be viewed through the transparent polyester layer against the titanium dioxide background provided by distribution of the pigment containing processing composition between Layer 9 and the polymeric image-receiving layer.

Film units, fabricated essentially as denoted above, may be processed in the stated manner, at processing temperatures of from about 100 to F., and may be exposed to a conventional step wedge to provide graphic illustration of the characteristic curves of the respective dye transfer images forming the multicolor dye positive images. Specifically, the detailed characteristic curves may be determined by plotting the density of the respective images to red, green and blue light, as a function of the log exposure of the photosensitive element, e.g., the characteristic cyan, magenta and yellow transfer image dye curves (red to red, green and blue reflected light) of the test and control film units.

As may be noted from examination of characteristic curves prepared in the stated manner, the previously described improvement in dye transfer image control and processing temperature latitude may be directly achieved by means of the present invention.

By addition of an effective concentration of and one U to the processing composition, image formation may be immediately viewed upon distribution of the processing composition by reason of the protection against incident radiation afforded the photosensitive silver halide emulsion layers by the compositions optical transmission density of about 6.0 density units and against the titanium dioxides effective reflective background afforded by reason of the composition possessing an optical reflection density of about 1.0 density units.

The pH and solvent concentration of the alkaline processing solution initially employed will possess a pH above the pKa of the optical filter agents where the latter are employed, that is, the pH at which about 50 percent of the agents are present as the lesser absorbing species and about 50 percent are present as the greater absorbing species, preferably a pKa of about 11 and most preferably about 12 and a pH at which the dye developers employed are soluble and ditfusible. Although it has been found that the specific pH to be employed may be readily determined empirically for any dye developer and optical filter agent, or group of dye developers and filter agents, most particularly desirable dye developers are soluble at pHs above 9 and relatively insoluble at pHs below 9, in reduced form, and relatively insoluble at substantially any alkaline pH, in oxidized form, and the system can be readily balanced accordingly for such dye developers. In addition, although as previously noted, the processing composition, in the preferred embodiment, will include the stated film-forming viscosity-increasing agent, or agents, to facilitate spreading of the composition and to provide maintenance of the spread composition as a structurally stable layer of the laminate, subsequent to distribution, it is not necessary that such agent be employed as a component of the composition.

Neutralizing means, for example, a polymeric acid layer of the type discussed above may be incorporated, as stated, in the film unit of the present invention, to provide reduction of the alkalinity of the processing solution from a pH above the pKa of the optical filter agent selected at which the dyes are soluble to a pH below the pKa of the agent at which the dyes are substantially nondiffusible, in order to advantageously further stabilize and optimize reflectivity of the dye transfer image. In such instance, the neutralizing layer may comprise particulate acid reacting reagent disposed within the film unit or a polymeric acid layer, for example, a polymeric acid layer approximating 0.3 to 1.5 mils in thickness, positioned intermediate the transparent support and image-receiving layer, and/or the opaque support and next adjacent emulsion/dye unit layer, and the film unit may also contain a polymeric spacer or barrier layer, for example, approximating 0.1 to 0.7 mil in thickness, next adjacent the polymeric acid layer, opposite the respective support layer, as previously described.

Specifically, the film units may employ the presence of a polymeric acid layer such as, for example, of the type set forth in US. Pat. No. 3,362,819 which, most preferably, includes the presence of an inert timing or spacer layer intermediate the polymeric acid layer carried on a support and the image-receiving layer.

As set forth in the last-mentioned patent, the polymeric acid layer may comprise polymers which contain acid groups, such as carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals, such as sodium, potassium etc., or with organic bases, particularly quaternary ammonium bases, such as tetramethyl ammonium hydroxide, or potentially acid-yielding groups, such as anhydrides or lactones, or other groups which are capable of reacting with bases to capture and retain them. The acid-reacting group is, of course, retained in the polymer layer. In the preferred embodiments disclosed, the polymer contains free carboxyl groups and the transfer processing composition employed contains a large concentration of sodium and/or potassium ions. The acid polymers stated to be most useful are characterized by containing free carboxyl groups, being insoluble in water in the free acid form, and by forming watersoluble sodium and/or potassium salts. One may also employ polymers containing carboxylic acid anhydride groups, at least some of which preferably have been converted to free carboxyl groups prior to imbibition. While the most readily available polymeric acids are derivatives of cellulose or of vinyl polymers, polymeric acids from other classes of polymers may be used. As examples of specific polymeric acids set forth in the application, mention may be made of dibasic acid half-ester derivatives of cellulose which derivatives contain free carboxyl groups, e.g., cellulose acetate hydrogen phthalate, cellulose acetate hydrogen glutarate, cellulose acetate hydrogen succinate, ethyl cellulose hydrogen succinate, ethyl cellulose acetate hydrogen succinate, cellulose acetate hydrogen succinate hydrogen phthalate; ether and ester derivatives or cellulose modified with sulfoanhydrides, e.g., with ortho-sulfobenzoic anhydride; polystyrene sulfonic acid; carboxymethyl cellulose; polyvinyl hydrogen phthalate; polyvinyl acetate hydrogen phthalate; polyacrylic acid; acetals of polyvinyl alcohol with carboxy or sulfo substituted aldehydes, e.g., o-, m-, or p-benzaldehyde sulfonic acid or carboxylic acid; partial esters of ethylene/maleic anhydride copolymers; partial esters of methyl-vinyl ether/maleic anhydride copolymers; etc.

As previously noted, the pH of the processing composition preferably is of the order of at least 12 to 14 and the pKa of the selected optical filter agents will accordingly preferably be in the order of 13 or greater. Thepolymer layer is disclosed to contain at least sufficient acid groups to effect a reduction in the pH of the image from a pH of about 12 to 14 to a pH of at least 11 or lower at the end of the imbibition period, and preferably to a pH of about to 8 within a short time after imbibition, thus requiring, of course, that the action of the polymeric acid be accurately so controlled as not to interfere with either development of the negative or imagetransfer of unoxidized dye developers. For this reason, the pH of the image layer must be kept at a functional transfer level, for example, 12 to 14 until the dye image has been formed after which the pH is reduced very rapidly to a pH below that at which dye transfer may be accomplished, for example, at least about 11 and preferably about pH 9 to 10. Unoxidized dye developers containing hydroquinonyl developing radicals diffuse from the negative to the positive as the sodium or other alkali salt. The diffusion rate of such dye image-forming components thus is at least partly a function of the alkali concentration, and it is necessary that the pH of the image layer remain on the order of, for example, 12 to 14 until transfer of the necessary quantity of dye has been accomplished. The subsequent pH reduction, in addition to its desirable effect upon image light stability, serves a highly valuable photographic function by substantially terminating further dye transfer.

In order to prevent premature pH reduction during transfer processing, as evidenced, for example, by an undesired reduction in positive image density, the acid groups are disclosed to be so distributed in the polymer layer that the rate of their availability to the alkali is controllable, e.g., as a function of the rate of swelling of the polymer layer which rate in turn has a direct relationship to the diffusion rate of the alkali ions. The desired distribution of the acid groups in the polymer layer may be effected by mixing acid polymer with a polymer free of acid groups, or lower in concentration of acid groups, and compatible therewith, or by using only an acid polymer but selecting one having a relatively lower proportion of acid groups. These embodiments are illustrated, respectively, in the cited copending application, by (a) a mixture of cellulose acetate and cellulose acetate hydrogen phthalate and (b) a cellulose acetate hydrogen phthalate polymer having a much lower percentage of phthalyl groups than the first-mentioned cellulose acetate hydrogen phthalate.

It is also there disclosed that the layer containing the polymeric acid may contain a water-insoluble polymer, preferably a cellulose ester, which acts to control or modulate the rate at which the alkali salt of the polymer acid is formed. As examples of cellulose esters contemplated for use, mention is made of cellulose acetate, cellulose acetate butyrate, etc. The particular polymers and combinations of polymers employed in any given embodiment are, of course, selected so as to have adequate wet and dry strength and when necessary or desirable suitable subcoats are employed to help the various polymeric layers adhere to each other during storage and use.

The inert spacer layer of the last-mentioned patent, for example, an inert spacer layer comprising polyvinyl alcohol or gelatin, acts to time control the pH reduction by the polymeric acid layer. This timing is disclosed to be a function of the rate at which the alkali diffuses through the inert spacer layer. It is there stated to have been found that the pH does not drop until the alkali has passed through the spacer layer, i.e., the pH is not reduced to any significant extent by the mere diffusion into the interlayer, but the pH drops quite rapidly once the alkali diffuses through the spacer layer.

As disclosed in aforementioned US. Pat. No. 3,362,819, the presence of an inert spacer layer was found to be effective in evening out the various reaction rates over a wlde range of temperatures, for example, by preventing premature pH reduction when imbition is effected at temperatures above room temperature, for example, at to F. By providing an inert spacer layer, that application discloses that the rate at which alkali is available for capture in the polymeric acid layer becomes a function of the alkali diffusion rates.

However, as disclosed in US. Pat. No. 3,455,686 preferably the aforementioned rate at which the cations of the alkaline processing composition, i.e., alkali ions, are available for capture in the polymeric acid layer should be decreased with increasing transfer processing temperatures in order to provide diffusion transfer color processes relatively independent of positive transfer image variations over an extended range of ambient temperatures.

Specifically, it is there stated to have been found that the diffusion rate of alkali through a permeable inert polymeric spacer layer increases with increased processing temperature to the extent, for example, that at relatively high transfer processing temperatures, that is, transfer processing temperatures above approximately 80 F., a premature decrease in the pH of the transfer processing composition occurs due, at least in part, to the rapid diffusion of alkali from the dye transfer environment and its subsequent neutralization upon contact with the polymeric acid layer. This was stated to be especially true of alkali traversing an inert spacer layer possessing permeability to alkali optimized to be effective with the temperature range of optimum transfer processing. Conversely, at temperatures below the optimum transfer processing range, for example, temperatures below approximately 40 F., the last-mentioned inert spacer layer was disclosed to provide an effective diffusion barrier timewise preventing effective traverse of the inert spacer layer by alkali having temperature depressed diffusion rates and to result in maintenance of the transfer processing environments high pH for such an extended time interval as to facilitate formation of transfer image stain and its resultant degradation of the positive transfer images color definition.

'It is further stated in the last-mentioned US. Pat. No. 3,455,686 to have been found, however, that if the inert spacer layer of the print-receiving element is replaced by a spacer layer which comprises a permeable polymeric layer exhibiting permeability inversely dependent on temperature, that is, a polymeric film-forming material which exhibits decreasing permeability to solubilized alkali derived cations such as alkali metal and quaternary ammonium ions under conditions of increasing temperature, that the positive transfer image defects resultant from the aforementioned overextended pH maintenance and/ or premature pH reduction are obviated.

As examples of polymers which were disclosed to exhibit inverse temperature-dependent permeability to alkali, mention may be made of: hydroxypropyl polyvinyl alcohol, polyvinyl methyl ether, polyethylene oxide, polyvinyl ozaxolidone, hydroxypropyl methyl cellulose, isopropyl cellulose, partial acetals of polyvinyl alcohol such as partial polyvinyl butyral, partial polyvinyl formal, partial polyvinyl acetal, partial polyvinyl propional, and the like.

The last-mentioned specified acetals of polyvinyl were stated to generally comprise saturated aliphatic hydrocarbon chains of a molecular weight of at least 1000, preferably of about 1000 to 50,000, possessing a degree of acetalation within about to 30%, to 80%, and 10 to 40%, of the polyvinyl alcohols theoretical polymeric hydroxy groups, respectively, and including mixed acetals where desired.

Where desired, a mixture of the polymers may be employed, for example, a mixture of hydroxypropyl methyl cellulose and partial polyvinyl vbutyral.

Employment of the detailed and preferred film units of the present invention, according to the herein described color diffusion transfer process, specifically provides for the production of a highly stable transfer image accomplished, at least in part, by effectively obviating the previously discussed disadvantages of the prior art products and processes, by in process adjustment of the environmental processing composition solvent and pH concentration from a solvent and pH concentration at which dye diffusion or transfer is operative to a solvent and pH concentration at which dye transfer is inoperative subsequent to substantial transfer image formation. The stable color transfer image is obtained irrespective of the fact that the film unit is maintained as an integral laminate unit during exposure, processing, viewing and storage of the unit. Accordingly, by means of the present invention, multicolor transfer images may be provided over an extended processing temperature range which exhibit desired maximum and minimum dye transfer image densities; yellow, magenta and cyan dye saturation; red, green and blue hues; and color separation. These unexpected advantages are in addition to the manufacturing obtained by reason of the present inventions integral color transfer film unit construction and which will be readily apparent from examination of the units parameters, that is, for example, advantages in more efficient utilization of fabricating materials and components, enhanced simplicity of film manufacture and camera design and construction, and more simplified and effectively controlled customer utilization of the unit.

The dimensionally stable support layers referred to may comprise any of the various types of conventional opaque and transparent rigid or flexible materials possessing the requisite liquid impermeability and, preferably, the vapor transmissivity denoted above, and may comprise polymeric films of both synthetic types and those derived from naturally occurring products. Particularly suitable materials include aqueous alkaline solution impermeable, water vapor permeable flexible polymeric materials such as vapor permeable polymeric films derived from ethylene glycol terephthalic acid, vinyl chloride polymers; polyvinyl acetate; polyamides; polymethacrylic acid methyl and ethyl esters; cellulose derivatives such as cellulose, acetate, triacetate, nitrate, propionate, butyrate, acetate-propionate, or acetate-butyrate; alkaline solution impermeable, water vapor permeable papers; crosslinked polyvinyl alcohol; regenerated cellulose; and the like.

As examples of materials, for use as the imagereceiving layer, mention may be made of solution dyeable polymers such as nylon as, for example, N-methoxymethyl polyhexamethylene adipamide; partially hydrolyzed polyvinyl acetate; polyvinyl alcohol with or without plasticizers; cellulose acetate with filler as, for example, one-half cellulose acetate and one-half oleic acid; gelatin; and other materials of a similar nature. Preferred materials comprise polyvinyl alcohol or gelatin containing a dye mordant such as poly-4-vinlypyridine, as disclosed in US. Pat. No. 3,148,061, issued Sept. 8, 1964.

It will be noted that the liquid processing composition employed may contain an auxiliary or accelerating developing agent, such as p-methylaminophenol, 2-4-diaminophenol, p-benzylaminophenyl, hydroquinone, toluhydroquinone, phenylhydroquinone, 4'-methylphenylhydroquinone, etc. It is also contemplated to employ a plurality of auxiliary or accelerating developing agents, such as a 3-pyrazolidone developing agent and a benzenoid developing agent, as disclosed in US. Pat. No. 3,039,869, issued June 19, 1962. As examples of suitable combinations of auxiliary developing agents, mention may be made of 1- phenyl-3-pyrazolidone in combination with p-benzylaminophenol and 1 phenyl 3-pyrazolidone in combination with 2,5 bis ethylenimino hydroquinone. Such auxiliary developing agents may be employed in the liquid processing composition or they may be initially incorporated, at least in part, in any one or more of the silver halide emulsion strata, the strata containing the dye developers, the interlayers, the overcoat layer, the imagereceiving layer, or in any other auxiliary layer, or layers, of the film unit. It may be noted that at least a portion of the dye developer oxidized during development may be oxidized and immobilized as a result of a reaction, e.g., an energy-transfer reaction, with the oxidation product of an oxidized auxiliary developing agent, the latter developing agent being oxidized by the development of exposed silver halide. Such a reaction of oxidized developing agent with unoxidized dye developer would regenerate the auxiliary developing agent for further reaction with the exposed silver halide.

In addition, development may be effected in the presence of an onium compound, particularly a quaternary ammonium compound, in accordance with the processes disclosed in US. Pat. No. 3,173,786, issued Mar. 16, 1965.

It will be apparent that the relative proportions of the agents of the diffusion transfer processing composition may be altered to suit the requirements of the operator. Thus, it is within the scope of this invention to modify the herein described developing compositions by the substitution of preservatives, alkalies, etc., other than those specifically mentioned, provided that the pH of the composition is initially at the first pH and solvent concentration required. When desirable, it is also contemplated to r include, in the developing composition, components such as restrainers, accelerators, etc. Similarly, the concentration of various components may be varied over a wide range and when desirable adaptable components may be disposed in the photosensitive element, prior to exposure, in a separate permeable layer of the photosensitive element and/or in the photosensitive emulsion.

In all examples of this specification, percentages of components are given by weight unless otherwise indicated.

Although the invention has been discussed in detail throughout employing dye developers, the preferred image-providing materials, it will be readily recognized that other, less preferred, difiusion transfer process dye image-providing materials may be substituted in replacement of the preferred dye developers in the practice of the invention. For example, there may be employed dye image-forming materials such as those disclosed in U.S. Pats. Nos. 2,647,049; 2,661,293; 2,698,244; 2,698,798; 2,802,735; 3,148,062; 3,227,550; 3,227,551; 3,227,552; 3,227,554; 3,243,294; 3,330,655; 3,347,671; 3,352,672; 3,364,022; 3,443,939; 3,443,940; 3,443,941; 3,443,943, etc., wherein color diffusion transfer processes are described which employ color coupling techniques comprising, at least in part, reacting one or more color developing agents and one or more color formers or couplers to provide a dye transfer image to a superposed image-receiving layer and those disclosed in US. Pats. Nos. 2,774,668 and 3,087,817, wherein color diffusion transfer processes are described which employ the imagewise differential transfer of complete dyes by the mechanisms therein described to provide a transfer dye image to a contiguous imagereceiving layer, and thus including the employment of image-providing materials in whole or in part initially insoluble or nondiffusible as disposed in the film unit which difiuse during processing as a direct or indirect function of exposure.

Where desired, the film unit may also contain ultraviolet absorbing materials to protect the mordanted dye transfer image from fading due to ultraviolet light such as those selected from the general class of benzotriazoles and benzophenones as, for example, the substituted 2- phenyl-benzotriazole agents disclosed in US. Pats. Nos. 3,004,896; 3,189,615; etc., the 2-hydroxybenzophenones such as 2 hydroxy-4-methoxybenzophenone; 2,2'-dihydroxy-4-methoxybenzophenone; 2-hydroxy-4-octyloxybenzophenone; etc., both water and organic solvent soluble agents being contemplated, and/or brightening agents such as those selected from the general class of triazinestilbenes, coumarins, anthracenes, terphenyls, tetraphenylbutadienes, quinoxalines, conventional for use as fluorescent agents and as optical brightening agents. Suitable triazinestilbene optical brightening agents are disclosed in US. Pat. No. 2,933,390; coumarines are disclosed in British Pat. No. 786,234; and various agents are disclosed in US. Pats. Nos. 2,171,427; 2,473,475; 2,595,030; 3,660,578; and British Pats. Nos. 595,065; 623,849; 624,051; 624,052; 678,291; 681,642; 705,406; etc. Commercially available brightening agents are distributed under the trade designation Tinopal (SP, WR, S'FG, BV277, 2B, GS, NG) Leucophor B, Calcofluor White MR, Blaneofor SC, Hitamine (BSP, N, SOL, 6T6), and the like, and commercially available ultraviolet absorbing agents are distributed under the trade designation Tinuvin and the like.

In general, ultraviolet absorbing and optical brightening agents may be employed in concentrations varying over an extended range. Suitable concentrations include those within the range of about 0.2 to 10 mgs./ft. of receptor layer surface area and, preferably, between about 1 to mgs./ft.

The agents may be incorporated in any one or more of the layers of the film unit intermediate the opaque layer and the viewing surface in any suitablemanner as, for example, a constituent component of the casting and/or coating solution or formulation employed to provide such layer or layers employing an organic solvent or water carrier or as a latex dispersion.

In the circumstances wherein the receptor layer possesses the dimensional stability to provide a self-sustaining layer conformation, the layer may optionally be coated on or carried by an appropriate dimensionally stable support layer of the various types and classes specifically designated hereinafter.

Ordinarily, when the image receptor stratum comprises a layer carried on a separate dimensionally stable support layer, the receptor stratum will comprise in the order 26 of about 0.1 to 0.4 mils in thickness whereas such stratum employed as a self-sustaining layer will comprise in the order of about 3 to 6 mils in thickness.

Although the preceding description of the invention has been couched in terms of the preferred photosensitive component construction wherein at least two selectively sensitized photosensitive strata are in continguous coplanar relationship and, specifically, in terms of the preferred tripack type structure comprising a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum having associated therewith, respectively a cyan dye developer, a magenta dye developer and a yellow dye developer, the photosensitive component of the film unit may comprise at least two sets of selectively sensitized minute photosensitive elements arranged in the form of a photosensitive screen wherein each of the minute photosensitive elements has associated therewith, for example, an appropriate dye developer in or behind its respective silver halide emulsion portion. In general, a suitable photosensitive screen will comprise minute redsensitized emulsion elements, minute green-sensitized emulsion elements and minute blue-sensitized emulsion elements arranged in side-by-side relationship in a screen pattern and having associated therewith, respectively, a cyan, a magenta and a yellow dye developer.

The present invention also includes the employment of a black dye developer and the use of a mixture of dye developers adapted to provide a black-and-white transfer image, for example, the employment of dye developers of the three subtractive colors in an appropriate mixture in which the quantities of the dye developers are proportioned such that the colors combine to provide black.

Where in the specification, the expression positive image has been used, this expression should not be interpreted in a restrictive sense since it is used primarily for purposes of illustration, in that it defines the image produced on the image-carrying layer as being reversed, in the positive-negative sense, with respect to the image in the photosensitive emulsion layers. As an example of an alternative meaning for positive image, assume that the photosensitive element is exposed to actinic light through a negative transparency. In this case, the latent image in the photosensitive emulsion layers will be a positive and the dye image produced on the image-carrying layer will be a negative. The expression positive image is intended to cover such an image produced on the imagecarrying layer.

It will be recognized that, by reason of the preferred film units structural parameters, the transfer image formed upon directed exposure of the film unit to a selected subject and processing, will be a geometrically reversed image of the subject. Accordingly, to provide transfer image formation geometrically nonreversed, exposure of such film unit should be accomplished through an image-reversing optical system such a camera possessing an image-reversing optical system.

In addition to the described essential layers, it will be recognized that the film unit may also contain one or more subcoats or layers, which, in turn, may contain one or more additives such as plasticizers, intermediate essential layers for the purpose, for example, of improving adhesion, and that any one or more of the described layers may comprise a composite of two or more strata of the same, or different, components and which may be contiguous, or separated from, each other, for example, two or more neutralizing layers or the like, one of which may be disposed intermediate the cyan dye image-forming component retaining layer and the dimensionally stable opaque layer.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpeted as illustrative and not in a limiting sense.

What is claimed is:

1. In a photographic diffusion transfer color process film unit which comprises a plurality of layers including a photosensitive silver halide layer having associated therewith a diffusion transfer process dye image-forming material and an image-receptive layer, adapted to receive dye image-forming material diffusing thereto, the improvement which comprises said dye image-forming material disposed in said film unit in the form of a dispersion of particulate material prepared by the process which comprises the steps of (a) dissolving the dye image-forming material and a polymer in a first solvent in which the material and the polymer are soluble; and

(b) distributing the polymer dye image-forming material first solvent solution in a second solvent in which the first solvent is miscible, the polymer is soluble and the dye image-forming material is insoluble.

2. A photographic diffusion transfer color process film unit as defined in claim 1 wherein said process for the preparation of said diffusion transfer process dye imageforming material dispersion includes the step of separating first solvent from the polymer dye image-forming material second solvent mixture prior to constitution of said dye image-forming material as a component of said film unit.

3. A photographic diffusion transfer color process film unit as defined in claim 2 wherein said process for the preparation of said diffusion transfer process dye imageforming material dispersion includes the step of separating second solvent from the polymer dye image-forming material second solvent mixture prior to constitution of said dye image-forming material as a component of said film unit.

4. A photographic diffusion transfer color process film unit as defined in claim 1 wherein said diffusion transfer process dye image-forming material particulate dispersion possesses a particle size distribution below the particle distribution at which a particulate dispersion exhibits a tyndall effect.

5. A photographic diffusion transfer color process film unit as defined in claim 1 wherein said diffusion transfer process dye image-forming material particulate dispersion possesses a particle size distribution possessing a mean particle size below about 0.01 micron.

6. A photographic diffusion transfer color process film unit as defined in claim 1 wherein said polymer soluble in said first solvent is adapted to coprecipitate with said diffusion transfer process dye image-forming material in said second solvent and is present in a concentration effective to substantially inhibit secondary particle growth of the particles forming the particulate dye image-forming material dispersion.

7. A photographic diffusion transfer color process film unit as defined in claim 1 including means for converting, subsequent to substantial dye transfer image formation in said layer adapted to receive dye image-forming material diffusing thereto, the pH of said film unit from a first processing pH to a second pH at which said dye transfer image exhibits increased stability.

8. A photographic diffusion transfer color process film unit as defined in claim 7 wherein said diffusion transfer process dye image-forming material is diffusible at said first processing pH as a function of the photoexposure of said film unit and is substantially nondiffusible at said second pH lower than said first pH.

9. A photographic diffusion transfer color process film unit as defined in claim 1 including opacifying agent, in a quantity sufficient to mask dye image-forming material associated with said photosensitive silver halide layer, adapted to be disposed intermediate said photosensitive silver halide layer and said layer adapted to receive dye image-forming material diffusing thereto.

10. A photographic diffusion transfer color process film unit as defined in claim 1 including means for contacting said photosensitive silver halide layerwith a processing composition.

11. A photographic diffusion transfer color process film unit as defined in claim 10 wherein said means for contacting said photosensitive layer with said processing composition comprises a rupturable container retaining said processing composition positioned extending transverse an edge of the film unit to effect, upon application of compressive pressure to said container, discharge of said containers processing composition contents into contact with said photosensitive silver halide layer.

12. A photographic diffusion transfer color process film unit as defined in claim 11 wherein said rupturable container retaining said processing composition is adapted, upon application of compressive pressure to the container, to discharge the containers processing composition contents intermediate said photosensitive layer and the layer adapted to receive dye image-forming material diffusing thereto.

13. A photographic diffusion transfer color process film unit as defined in claim 12 wherein said processing composition includes opacifying agent in a quantity sufficient to mask dye image-forming material associated with said photosensitive layer.

14. A photographic diffusion transfer color process film unit as defined in claim 13 including a dimensionally stable opaque layer positioned contiguous the surface of said photosensitive layer opposite said layer adapted to receive dye image-forming material diffusing thereto.

15. A photographic diffusion transfer color process film unit as defined in claim 14 including dimensionally stable transparent layer positioned contiguous the surface of said layer adapted to receive dye image-forming material diffusing thereto opposite said photosensitive layer.

16. A photographic diffusion transfer color process film unit as defined in claim 11 including a dimensionally stable transparent layer positioned contiguous the surface of said photosensitive silver halide layer opposite said layer adapted to receive dye image-forming material diffusing thereto, an opaque layer adapted to reflect incident visible radiation positioned intermediate said photosensitive silver halide layer and the layer adapted to receive dye image-forming material diffusing thereto and said rupturable container retaining said processing composition is adapted, upon application of compressive pressure to the container, to discharge the containers processing composition contents intermediate said photosensitive silver halide layer and said dimensionally stable transparent layer.

17. A photographic diffusion transfer color process film unit as defined in claim 1 wherein said dye image-forming material is a dye which is a silver halide developing agent.

18. A photographic diffusion transfer color process film unit as defined in claim 1 including at least two selectively sensitized silver halide layers each having a dye image-forming material associated therewith.

19. A photographic diffusion transfer color process film units as defined in claim 18 wherein each of the selectively sensitized silver halide layers possesses predominant spectral sensitivity to separate regions of the spectrum and the dye image-forming material associated with each of said silver halide layers possesses a spectral absorption range subsequent to processing substantially complementary to the predominant sensitivity range of its associated silver halide layer.

20. In a photographic diffusion transfer color process film unit as defined in claim 19 which comprises, in combination:

a photosensitive element including a composite structure containing, as essential layers, a dimensionally stable opaque layer;

at least two selectively sensitized silver halide emulsion layers possessing predominant spectral sensitivity to separate regions of the visible electromagnetic spectrum, said silver halide emulsion layers having associated therewith a dye which is a silver halide developing agent and is soluble and diifusable, in alkaline processing composition, at a first pH, possessing a spectral absorption range subsequent to processing substantially complementary to the predominant sensitivity range of its associated emulsion layer;

an alkaline solution dyeable polymeric layer;

a polymeric layer elfective subsequent to substantial dye transfer image formation in said dyeable polymeric layer to reduce alkaline processing composition possessing said first pH at which said dyes are soluble and diifusible to a second pH at which said dyes are substantially nondiffusible;

a dimensionally stable transparent layer; and

means securing the layers in substantially fixed relationship; and

a rupturable container retaining an alkaline processing composition possessing said first pH at which said dyes are soluble and difl usible and opacifying agent in a quantity sufiicient to mask dye associated with said selectively sensitized silver halide emulsion layers, said rupturable container positioned and extending transverse an edge of the photosensitive element to effect unidirectional discharge of the containers alkaline processing composition intermediate the dyeable polymeric layer and the selectively sensitized silver halide emulsion layer next adjacent thereto;

the improvement which comprises said dyes disposed in said film unit in the form of a dispersion of particulate material prepared by:

(a) dissolving dye and polymer in a first solvent in dwhich the dye and the polymer are soluble; an

(b) distributing the polymer dye first solvent solution in a second solvent in which the first solvent is miscible, the polymer is soluble and the dye is insoluble.

21. In a photographic diffusion transfer color process film unit as defined in claim 19 adapted to be processed by passage of said unit between a pair of juxtaposed pressure-applying members and which comprises, in combination:

a photosensitive element including a composite structure containing, as essential layers, in sequence, a dimensionally stable alkaline solution impermeable opaque layer;

a red-sensitive silver halide emulsion layer having associated therewith cyan dye;

a green-sensitive silver halide emulsion layer having associated therewith magenta dye;

a blue-sensitive silver halide emulsion layer having associated therewith a yellow dye, said cyan, magenta and yellow dyes comprising silver halide developing agents soluble and diffusible, in alkaline processing composition, at a first pH;

an alkaline solution dyeable polymeric layer;

a polymeric layer containing acidic material in a concentration adapted to effect reduction of a processing composition having said first pH at which said cyan, magenta and yellow dyes are soluble and diffusible to a second pH at which said cyan, magenta and yellow dyes are substantially nondiffusible;

a dimensionally stable alkaline solution impermeable transparent layer; and

means securing said layers substantially in fixed relationship; and

a rupturable container retaining an aqueous alkaline processing composition having said first pH at which said cyan, magenta and yellow dyes are soluble and ditlusible and opacifying agent in a quantity sufiicient to mask, upon distribution of the aqueous alkaline processing composition as a layer, intermediate the dyeable polymeric layer and said blue-sensltive silver halide emulsion layer, cyan, magenta and yellow dye associated with said red-, greenand blue-sensitive emulsion layers, said container fixedly positioned and extending transverse an edge of the photosensitive element to effect, upon application of compressive force to said container, unidirectional discharge of the containers aqueous alkaline processing composition contents intermediate said dyeable polymeric layer and said blue-sensitive silver halide emulsion layer;

the improvement which comprises at least one of said cyan, magenta and yellow dyes disposed in said film unit in the form of a dispersion of particulate material prepared by:

(a) dissolving the dye and a polymer in a first solvent comprising water at a pH at which the dye and the polymer are soluble and the polymer soluble in the first solvent is adapted to coprecipitate with the dye in a second solvent comprising water at a pH at which the dye is insoluble and the polymer is soluble; and

(b) converting the polymer dye first solvent solution to the polymer dye second solvent mixture by changing the pH of the first solvent to the pH of the second solvent at which the polymer is soluble and the dye is insoluble and coprecipitates with polymer.

22. A process of forming transfer images in color which comprises, in combination, the steps of:

(a) exposing a photographic film unit which comprises a plurality of layers including a photosensitive silver halide layer having associated therewith a diifusion transfer process dye image-forming material in the form of a dispersion of particulate material prepared by:

(1) dissolving the dye image-forming material in a first solvent in which the material is soluble;

(2) dissolving in the first solvent a polymer soluble in said first solvent and adapted to coprecipitate with the solubilized dye image-forming material in a second solvent in which the dye image-forming material is insoluble and the polymer is soluble; and

(3) distributing the polymer dye image-forming material first solvent solution in a second solvent in which the dye image-forming material is insoluble and the polymer is soluble and coprecipitates;

and an image-receptive layer, adapted to receive dye image-forming material difiusing thereto;

(b) contacting said photosensitive silver halide layer with an aqueous alkaline processing composition;

(c) effecting thereby development of the photoexposed silver halide layer;

(d) forming thereby an imagewise distribution of diffusible dye image-forming material, as a function of the point-to-point degree of the silver halide layers exposure to incident actinic radiation; and

(e) transferring, by diffusion, at least a portion of said imagewise distribution of said ditfusible dye imageforming material to said image-receptive layer to provide a dye image to said layer in terms of said imagewise distribution.

23. A process of forming transfer images in color as defined in claim 22 wherein said film unit includes means for reducing, subsequent to substantial dye transfer image formation, the pH of said film unit from a first processing pH to a second pH at which a dye transfer image exhibits increased stability and including the step of reducing the pH of the film unit from said first processing pH to said second pH subsequent to substantial dye transfer image formation.

24. A process of forming transfer images in color as defined in claim 23 wherein said diffusion transfer process dye image-forming material is diffusible at said first processing pH as a function of the photoexposure of said film unit and is substantially nondiffusible at said second pH lower than said first pH and including the step of re ducing the pH of said film unit from said first processing pH to said second pH at which said dye image-forming material is substantially nondiffusible, subsequent to substantial dye transfer image-formation.

25. A process of forming transfer images in color as defined in claim 22 wherein said dye image-forming material is a dye which is a silver halide developing agent.

26. A process of forming transfer images in color as defined in claim 22 wherein said photosensitive element comprises in contiguous relationship at least two selectively sensitized silver halide layers having associated therewith a dye image-forming material which is diffusible during processing as a function of the point-to-point degree of the photoexposure of its associated silver halide layer.

27. A process of forming transfer images in color as defined in claim 26 wherein said selectively sensitized silver halide layers possess predominant spectral sensitivity to separate regions of the visible spectrum and the dye image-forming material associated with each of said emulsion layers provides a dye possessing subsequent to processing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion layer.

28. A process of forming transfer images in color as defined in claim 27 wherein said photosensitive element contains, as essential layers, in sequence, a support layer; a red-sensitive silver halide emulsion layer having associated therewith cyan dye; a green-sensitive silver halide emulsion layer having associated therewith magenta dye; a blue-sensitive silver halide emulsion layer having associated therewith yellow dye, each of said cyan, magenta and yellow dyes being a silver halide developing agent.

29. A process of forming transfer images in color as defined in claim 22 wherein said film unit possesses a rupturable container retaining said aqueous alkaline processing composition positioned extending transverse an edge of said film unit adapted to effect, upon application of compressive pressure to said container, discharge of said containers processing contents into contact with said photosensitive silver halide layer, and including the step of applying compressive pressure to said container and discharging said containers processing composition contents into contact with said photosensitive layer.

30. A process of forming transfer images in color as defined in claim 29 wherein said aqueous alkaline processing composition includes an opacifying agent.

31. A process of forming transfer images in color as defined in claim 29 wherein said aqueous alkaline processing composition is discharged intermediate said photosensitive silver halide layer and said image-receptive layer.

32. A process of forming transfer images in color as defined in claim 22 wherein said film unit contains a processing composition permeable opaque layer disposed intermediate said photosensitive silver halide layer and said image-receptive layer.

References Cited UNITED STATES PATENTS 3,382,073 5/1968 Land 9677 3,415,644 12/1968 Land 96-3 3,438,775 4/1969 Kasman et al. 96-3 RONALD H. SMITH, Primary Examiner R. L. SCHILLING, Assistant Examiner U.S. Cl. X.R. 9629 D, 77, 97 

